Psoriasis is a common cutaneous disease, affecting approximately two percent of the U.S. population. Classic plaque like psoriasis is the most common form of the disease which most typically manifests itself in erythematous lesions with silvery scales on the elbows, knees, sacrum, buttocks and scalp. The degree of physical and psychological disability ranges from slight to devastating. And, while there are a number of treatments, including topical medications, phototherapy and internal medications, the literature states that psoriasis is incurable. See Stiller, M. J., A Management Update on Psoriasis, Hospital Medicine, January 1994, pp. 28-35.
In the art of treating certain types of skin lesions, warts, pre-cancerous and cancerous lesions, cryotherapy is a known treatment modality. However, cryotherapy has not previously been reported as a psoriasis treatment. Two main techniques for cryosurgery are reported in the literature. Namely, a spray technique (ST) in which cryogen is applied directly onto the target site and a cryoprobe technique (CP) in which the surface of a probe, (that has been previously cooled by the cryogen), is applied to the target site instead of the actual cryogen. The objective of state of the art cryogenic therapy is destruction of the tissue. This destruction is the result of freezing of the tissue and transformation of water within the tissue into biologically inert ice crystals. This leads to cessation of circulation in the tissues with intra- and extra-cellular biochemical, anatomical and physiological sequel the end of which is tissue anoxemia and ischemic necrosis. It is known that, as a result of this freezing, a bullae of fluid develops in the areas treated. Subsequently, the damaged tissue on top of the bullae separates and sloughs off and the new skin below the fluid becomes the new surface. In U.S. Pat. No. 4,802,475, issued to A. H. A. G. Weshahy on Feb. 7, 1989, a novel probe for applying intralesional cryotherapy with the CP technique and a method for using the same is described. Further, in U.S. Pat. No. 4,865,028, issued to W. J. B. Swart on Sep. 12, 1989, discloses a device for carrying out cryotherapy. Further patents for treating skin conditions include U.S. Pat. No. 3,946,733, issued to J. S. Han on Mar. 30, 1976, for a moxibustion apparatus and U.S. Pat. No. 4,784,135, issued to S. E. Blum on Nov. 15, 1988, for far ultraviolet surgical and dental procedures. What has been missing from the art is a method of cryogenically treating psoriasis, without causing tissue anoxemia and ischemic necrosis of the tissues below the lesion, and which substantially reduces the chance of recurrence of the psoriatic lesion in the same location.
Accordingly, it is an object of the present invention to provide a method of cryogenically treating psoriatic lesions.
Another object of the present invention is to provide a method of cryogenically treating psoriatic lesions which does not result in destruction of the underlying tissue layer.
Still another object of the present invention is to provide a method of cryogenically treating psoriasis which substantially decreases the chance of recurrence of the psoriatic lesion in the same localized area of a patient's body.
Other objects and advantages over the prior art will become apparent to those skilled in the art upon reading the detailed description as follows.